National origin discrimination involves treating a job applicant or employee unfavorably because of that person's national origin—which includes birthplace, country or region of origin, ethnicity (actual or perceived), ancestry, culture, or linguistic characteristics (accent, etc.). National origin discrimination also can involve treating people unfavorably because they are married to or associated with a person of a certain national origin.

National origin discrimination is a form of employment discrimination that violates federal law—including Title VII of the Civil Rights Act of 1964 (42 U.S.C. §2000e). States also have laws against national origin discrimination in employment. These laws are generally located in a state’s statutes—often in the labor code or employment-related statutes.

The law makes it illegal for an employer or other covered entity to use an employment policy or practice that applies to everyone—regardless of national origin—if it has a negative impact on people of a certain national origin and is not job-related or necessary to the operation of the business.

An employer can only require an employee to speak fluent English if fluency in English is necessary to perform the job effectively. An English-only rule that requires employees to speak only English on the job is only allowed if it is needed to ensure the safe or efficient operation of the employer's business and is put in place for nondiscriminatory reasons. An employer may not base an employment decision on an employee's foreign accent, unless the accent seriously interferes with the employee's job performance.
Discrimination can occur when the victim and the person who inflicted the discrimination are the same national origin.

It is also unlawful to harass a person in the workplace because of his or her national origin. Harassment can include, for example, offensive or derogatory remarks about a person's national origin, accent, or ethnicity. Although the law doesn't prohibit simple teasing, offhand comments, or isolated incidents that are not very serious, harassment is illegal when it is so frequent or severe that it creates a hostile or offensive work environment or when it results in an adverse employment decision—such as the victim being fired or demoted.

The harasser can be the victim's supervisor, a supervisor in another area, a co-worker, or someone who is not an employee of the employer, such as a client or customer.

The law forbids discrimination when it comes to any aspect of employment, including hiring, firing, pay, job assignments, promotions, layoff, training, fringe benefits, and any other term or condition of employment.

In New York, national origin discrimination in employment is prohibited under both federal and state law. Federally, Title VII of the Civil Rights Act of 1964 makes it illegal to discriminate against an individual because of their national origin, which encompasses a range of factors including birthplace, ethnicity, ancestry, and linguistic characteristics. New York State law also prohibits such discrimination, offering protections through statutes such as the New York State Human Rights Law. Employers are not allowed to implement policies that negatively impact individuals of a certain national origin unless the policy is necessary for the job and the business's operation. English-only rules at work are permissible only when they are essential for the safe or efficient operation of the business and are implemented for non-discriminatory reasons. Furthermore, it is illegal to make employment decisions based on an employee's foreign accent unless it significantly interferes with job performance. Workplace harassment based on national origin is also unlawful, especially when it leads to a hostile work environment or adverse employment actions like termination or demotion. The law covers all aspects of employment, from hiring to job conditions, and applies to employers, co-workers, and even non-employees like clients or customers.